Ejemplo n.º 1
0
        public SqliteDataReader ExecuteReader(CommandBehavior behavior, bool want_results, out int rows_affected)
        {
            Prepare();

            // The SQL string may contain multiple sql commands, so the main
            // thing to do is have Sqlite iterate through the commands.
            // If want_results, only the last command is returned as a
            // DataReader.  Otherwise, no command is returned as a
            // DataReader.

            IntPtr psql;             // pointer to SQL command

            // Sqlite 2 docs say this: By default, SQLite assumes that all data uses a fixed-size 8-bit
            // character (iso8859).  But if you give the --enable-utf8 option to the configure script, then the
            // library assumes UTF-8 variable sized characters. This makes a difference for the LIKE and GLOB
            // operators and the LENGTH() and SUBSTR() functions. The static string sqlite_encoding will be set
            // to either "UTF-8" or "iso8859" to indicate how the library was compiled. In addition, the sqlite.h
            // header file will define one of the macros SQLITE_UTF8 or SQLITE_ISO8859, as appropriate.
            //
            // We have no way of knowing whether Sqlite 2 expects ISO8859 or UTF-8, but ISO8859 seems to be the
            // default.  Therefore, we need to use an ISO8859(-1) compatible encoding, like ANSI.
            // OTOH, the user may want to specify the encoding of the bytes stored in the database, regardless
            // of what Sqlite is treating them as,

            // For Sqlite 3, we use the UTF-16 prepare function, so we need a UTF-16 string.

            if (parent_conn.Version == 2)
            {
                psql = Sqlite.StringToHeap(sql.Trim(), parent_conn.Encoding);
            }
            else
            {
                psql = Marshal.StringToHGlobalUni(sql.Trim());
            }

            IntPtr pzTail = psql;
            IntPtr errMsgPtr;

            parent_conn.StartExec();

            rows_affected = 0;

            try {
                while (true)
                {
                    IntPtr pStmt;

                    GetNextStatement(pzTail, out pzTail, out pStmt);

                    if (pStmt == IntPtr.Zero)
                    {
                        throw new Exception();
                    }

                    // pzTail is positioned after the last byte in the
                    // statement, which will be the NULL character if
                    // this was the last statement.
                    bool last = Marshal.ReadByte(pzTail) == 0;

                    try {
                        if (parent_conn.Version == 3)
                        {
                            BindParameters3(pStmt);
                        }

                        if (last && want_results)
                        {
                            return(new SqliteDataReader(this, pStmt, parent_conn.Version));
                        }

                        ExecuteStatement(pStmt);

                        if (last)                         // rows_affected is only used if !want_results
                        {
                            rows_affected = NumChanges();
                        }
                    } finally {
                        if (parent_conn.Version == 3)
                        {
                            Sqlite.sqlite3_finalize(pStmt);
                        }
                        else
                        {
                            Sqlite.sqlite_finalize(pStmt, out errMsgPtr);
                        }
                    }

                    if (last)
                    {
                        break;
                    }
                }

                return(null);
            } finally {
                parent_conn.EndExec();
                Marshal.FreeHGlobal(psql);
            }
        }